python getting json values from list

Question

I have some json data similar to this...

    {
        "people": [
            {
                "name": "billy",
                "age": "12"
                 ...
                 ...
            },
            {
                "name": "karl",
                "age": "31"
                 ...
                 ...
            },
            ...
            ...
        ]
    }

At the moment I can do this to get a entry from the people list...

wantedPerson = "karl"

for person in people:
    if person['name'] == wantedPerson:
        * I have the persons entry *
        break

Is there a better way of doing this? Something similar to how we can .get('key') ? Thanks, Chris

If you want to do this search multiple times, you could re-structure the data first. Otherwise there isn't any improvement to make. Keep in mind that there is no such thing as "a json object" - json data is parsed to create ordinary Python dicts, lists etc. After that, the rules are exactly the same as if you had created the data in any other way. — Karl Knechtel
– Karl Knechtel, Commented Sep 27, 2021 at 21:20

Grismar · Accepted Answer · 2021-09-27 21:33:44Z

1

Assuming you load that json data using the standard library for it, you're fairly close to optimal, perhaps you were looking for something like this:

from json import loads

text = '{"people": [{"name": "billy", "age": "12"}, {"name": "karl", "age": "31"}]}'

data = loads(text)

people = [p for p in data['people'] if p['name'] == 'karl']

If you frequently need to access this data, you might just do something like this:

all_people = {p['name']: p for p in data['people']}

print(all_people['karl'])

That is, all_people becomes a dictionary that uses the name as a key, so you can access any person in it quickly by accessing them by name. This assumes however that there are no duplicate names in your data.

answered Sep 27, 2021 at 21:33

Grismar

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Comments

Aviv Shabi · Accepted Answer · 2021-09-27 21:35:39Z

1

First, there's no problem with your current 'naive' approach - it's clear and efficient since you can't find the value you're looking for without scanning the list.

It seems that you refer to better as shorter, so if you want a one-liner solution, consider the following:

next((person for person in people if person.name == wantedPerson), None)

It gets the first person in the list that has the required name or None if no such person was found.

answered Sep 27, 2021 at 21:35

Aviv Shabi

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Comments

miroslav licko · Accepted Answer · 2021-09-27 22:02:35Z

0

similarly

ps =  {
        "people": [
            {
                "name": "billy",
                "age": "12"
    
            },
            {
                "name": "karl",
                "age": "31"
            },
        ]
    }

print([x for x in ps['people'] if 'karl' in x.values()])

For possible alternatives or details see e.g. # Get key by value in dictionary

answered Sep 27, 2021 at 22:02

miroslav licko

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